PROCEDURE IN DESIGN OF D.C. GENERATOR 219 



(Fig. 79) draw a straight line to the point on the datum line 

 immediately below the pole tip, in order to obtain the curve A 

 of flux distribution on open circuit, all as explained on page 

 131 (Art. 41). Measure the area of this flux curve, and draw 



11000 



10000 



"0 1000 2000 3000 4000 5000 6000 7000 8000 



Ampere -Turns per Pole 

 FIG. 82. Saturation curves for air-gap, teeth, and slots. 



the dotted rectangle of equal area. The height of this rectangle 

 represents the average air-gap density over the pole pitch, and 



::./ N 6,430,000 



its numerical value is B g (average) = 645 " 15 34 X 11 = 



5,910 gausses. 



Using this length as a scale for measuring other ordinates of the 



